Tag Archives: VSS

VSS diagnostics

For the past eight month, I’ve been working with EMC and Microsoft to diagnose a problem. Several time a month, during the backup of our primary Windows 2008 R2 file server, all the VSS shadow copies get deleted for the volume containing all our shared departmental directories.

This has two major effects. First, it means that our clients no longer can recover files using the Previous Versions feature of Windows. Second, it casts significant doubt on the validity of the backups performed at that time, which EMC NetWorker reports as having completed successfully.

We have been unable to find a technical solution to the shadow copy loss, so we will be reconfiguring our storage and shared directories to accommodate the limitations of NetWorker. In the meantime, I want to note a few of resources that have been helpful in diagnosing problems with VSS (it will be easier to find them here than in my pile o’ email):

Volume Shadow Copy Service (TechNet)

Volume Shadow Copy Service (MSDN)

Registry Keys and Values for Backup and Restore

How to enable the Volume Shadow Copy service’s debug tracing features in Microsoft Windows Server 2003 and Windows 2008

Using Tracing Tools with VSS

Script: Shadow Copy Report

We use EMC NetWorker for our enterprise backup solution. Since we migrated our primary file server from a NetApp filer to a native Windows server, we’ve been having a recurring problem with all the Shadow Copies for a volume getting deleted. There are strong indications that the problem is related to the NetWorker backups.

As we have been working on this issue with EMC (since the first week in January!), I wrote a script to tell me two things each morning; how many snapshots exist for each volume, and what VSS errors were logged, if any.

I thought someone might find it useful, so I’ve posted it as a separate page (the script doesn’t fit nicely in the column on the blog).

PowerShell Script: chksnap.ps1